Telegraph system.



. *UNITED sTATEs PATENT Y JOHNHUME BELL-gbr EAST ORANGE.' NEW JERSEY, 'AssIGNoR To WESTERN ELECTRIC COMPANYy INCORPORATED, OF NEW YORK, Y., CORPORATION OF NEW YORK.

' TELEGRAPH SYSTEM.

To all inkom it may concern:

Be it known that I, JoHNlH. BELL, a citizen of the United States, residing at East Orange, in the count-y ot Essex and State ot New Jersey, have invented certain new and useful -Improvements in Telegraph Systems, ofwhich the following is a full, clear,

1 cating variation of electrical characteristics in the circuits of duplex` telegraph systems or equipments, wherein it is required `to maintain predetermined conditions of electrical balance between a pluralityA offcircuits.`

In carrying out the present invention,

there is provided a plurality of current indicating devices and adjustable circuit controlling means therefor to be included with i electrically balanced-circuits in a manner to indicate variations of balance greater than predetermined range limitsbetween the circuits.

This invention is illustrated in the accompanying drawing, in which-portions of the equipment nare shown diagranmiatically,

while other portions thereof are shown 1n perspective. The embodiment chosen for illustrating the features of the present invention has been planned in connection with telegraph duplex systems, and in'order to 'simplify the drawing only so much of a telegraphic equipment is shown as'will be'v necessary to a clear understanding of the inven-l tion.

In the drawing, Figure l -illustrates the application of this invention to, a differential duplex polar type telegraphic equipment; Fig. 2 shows the invention applied to a bridge duplex telegraphic equipment; Fig.- 3 illustra-tes an alternate circuit arrangement for a signal control relay; and Fig. 4 shows a` proposed arrangement for adjustable contacts to be operated by current indicating meters employed in this system.

Briefly described, his system provides ythat a current indica-ting meter equipped withcontacts under control of its hand or needle will be included one in the circuit of the main line, and one in the artificial line of a duplex telegraph equipment. Relays Specification of Letters Patent.

' Patented Mar. 11, 1919.l

Application filed August 1, 1917. Serial No. 183,868.

under control of the meter contacts in turn c ontrol the operation of visual and audible signals.- The meter contacts are arranged to be adjustably moved with respect to the path comprising an adjustable resistance 11 to earth, while a second path is formed' through anadjustable resistance 12 and an V'adjustable or variable condenser 13 to earth.

Telegraphic duplex vequipments being well known in the art, it will,therefore, be obvious that a conductor 6 may be included with suitable telegraph transmitting equipment, while the conductor 7 may be included with a suitable telegraph receiving equipment for respectively 'transmitting' outgoing impulses and for receiving incoming impulses by way of the line conductor 1. It will also be obvious that through adjustment f of the variable resistances 11 and 12 and the variable condenser 13 the electrical characteristics ofthe artiicial line 10 may be calibrated to correspond or balance with the electrical characteristics of the main line 1. The connective point for such balance of electrical condition -between the artificial line 10 and the main line 1 being present at the apex or neutral point 5, intermediate the coils 3 and 4 of the line relay 2. In the presenttelegraph system it will be understood the line conductor l extends toa distant'station (not shown) at which it may preferably be provided with equipment similar to the 4duplex apparatus. shown, thereby permitting messages to be transmitted simultaneously in each direction between the two stations, on the well known two-current basis.

Referring to Fig. 4 of the drawing an A clamping 'actinlof'e'spective Wing nuts 56 'and 58 engaging suitably iiXe'd members .(not shovvn),', Contact spring members 59 and 60, 61 and62 carried by the bracketsw and,

57 respectively,. arze\'insulate d one from ane other :and/also fronitheir supporting brackets. The 4zero or no 'current position of the. needlex53 -is at acentral point on the scale' 54:- as -conventionally indicated lby the zero character. rllherefore, current action in 4a given direction through fthe coil 50 Will causel thev needle-1 to'be 'deflected to-one. side, While I current 'action in thev opposite direction through the coil causes the needle to be de? e'cted to the,y .opposite side. ln' cas'e a strength of current in thecol-.50 is suiii'cient theneedle 53 will -loej deflected to. reach and'V exert pressure to flex the vspringv59 to estab lish contact with its associated contact menr here() or to, flex thespring 61 into. contact '.Qvith'its associated contact memiber 62, ac-

cording tothe direction of the current 'i through the coil 50. lt Will be obvious that by. slnitingthe position of the contact memhers 59. to 61, with relation to the zeropoint on the scale 5st, the? contacts will remain inactive for currentsv of a predetermined strength through the moving coil 50z .but Willbecome' active -under.l currents inexcess-of such pre= Idetermined value. 'lt yWill be understood that `in substitution of tvvo contact members .t'eachside of .the needle 53 an alternate ar.- rangement Would correspond with the schematic' Aor circuit illustration shown in connfecticn With'the meters. in Figs. 1 and '2.

ln adapting the apparatus shown in `Fig. Ll-

to this alternate arrangement the contact' 1 members'v 60 and 62 may be .dispensed with `and* the needle 53 connected to form a contact Yinem-ber to engage either' one or `the other of the remaining contact members 59 and laccording'tothe direction in which the needle may- 'hedeilec'ted irtererring to Fig, 1, letit be assu-med for purposes; of4l description. that, the artificial line conductor 'has beenlelectrically'calibiated or balancedjvith the' line conductor 1, and that the characteristics of these' circuits are Isuch' that on ,the 'proper inclusion of current sources havingpredetermined po-l tentials With the conductory 6, as' through'a telegraph. transmitter, a current of ifty- 'mil` liamfperes will bem'aintained-inthe artificial line' 101. While* current of. av corresponding strength will also beinaintained in theline A, conductor 1. Currentso suclr'strengths may he taken. a's Working-'values .for the v transmission' of message impulses. "Therel fore, let it be further assumed that in setting predetermined range limits for-such .currentstrengths'the contacts .22 and 23., 32 andyof ithe lrnilliarnmeters and '30 rese'ctively are adjusted. adjacent 4points on e meter scales corresponding with Vfifty-ve milliamperes. W ith such settings of the mesulation of the.` line l becomes lower mascia f ter contacts it -ivillbe obvious thatl so; long.; as the calihratedjcircuit conditionhffth'e'" telegraph system remains 'unchangedfthe ",lile'wf" ter needles, n regularly. responding toftele-i' v` graphic impulses,- willl not-be deflected vbeyond the predetermined points correspond- -ig wat fifty mnamperes, and, therefore, Y" i the associated contacts 'Will not'be closed..A

Assumingnow that'for some reason, say, l

a change fromldry 'to 'rainy `Weathel: AthA vlto the extent that leakage'therefrom Would "redce its. resistance condition with respect, tothe earth to an eXten/t that thesourc'es oiground-v 1 80 ed current assumed to be included yjte-le? graphically with the conductor' 6. mayde- Lelop a current equal to or in excess of iifty- .lvKnilliamperesthrough the meter l20.` @tchincrease of currentl strength Wouldcafikse /tlie needle 21 to engagefits contact phase with changes in polarity.' of

the telegraphic' impulses, thereby` including a source of current 2A, through the Winding of a relay to earth. Y Assuming '-thatla switch is on its point 42, operation ofgthe relay .25 establishes a circuit lfrom'a-source of current 44, through the Windingoj'afrelay 45, a lamp signal ,27, thencezfoverthe contacts 2li-of the relay .25, .t0`earth. The lamp 27 is thereby lighted and the-relay- 46 operated to include .throughits .contacts-4o,

the current 'source ,ftwith a, signal lbell 47 Operation of the audible signal i7 notilies an attendant, and manifestation of the visual l signal 27l denotes that the unbalance 'is due' to a reduced resistance condition of. the line .1, whereupon the adjustable devices 11, 12' l'and 13 of the artiicial line 'may be irrimediv ately moved to lovver the resistance thereofto such point that readings of the telegraphic impulses ongthe meters 20 and 30 AWill indicate When a new balance has been l estab-l lished vto meet the change in electricalcharacteristics of the main? line 1. `On account ofthis new balance of the duplex circuits, increase of currentstrength -Will be present through the milliammeters 20 and 30; there- `fore, toprovide operating margins to meet the rainy .Weather conditions, .let 'it' now be assumed that a change to clear Weather and a corresponding drying of the line 1 takes' place, theigby increasing' the resistance of the line with respectto -the earth. In accordance with usual telegraph'practice, let it be assumed that resistance units or equivalents therefor usually employed as battery protective devices are present intermediate the sources of current and the telegraph transmitter assumed as included with the conductor 6. Such condition in the current supply circuit is accordingly accumulative with other characteristics manifested in the telegraph system, due to the increase in insulation resistance of the line 1, wherebya higher current potential 'will be present at the neutral point 5 of the duplex equipment, all as may be readily apparent by application of Ohms law. It follows, therefore, that, .due to the increase in potential of outgoing telegraphic impulses at the neutral respect to the artilicial line and the line 1..; The contacts 22 and 23, 32 and 33 mayacf.. vcordingly be readjusted to predeterminedv lpoints on the ammeter scales beyond which fluctuations of balance .range must not be point 5, currents of greater strength will flow through the milliammeter 30.0f the artilicial line 10.' Thel greater amplitude of movement imparted by these vcurrents tothe needle 31 will cause it to reach its contacts 32-33 in phase with the polarity ofthe current impulses, whereupon the current source 34 will be included to operate the relay 35 to in turn energize asignal 37 and the relay l44 and through the latter relay ell'ect operation of the bell 47, -as already described. Such energized condition of the signal'37 indicates that the unbalancerof the duplex circuit is due to a higher resistance condition in the line circuit 1. Therefore, the adjustabledevices 11, 12 and 13 ofthe artificial line may be readjusted to increase the resistancerthereof until the ammeters and under telegraphic impulses will indicate that a new balance has been established with permitted to extend without attention being called thereto by the signals as described.

vReferring to Fig. 2 of the drawing, it will b'e `noted that the equipment shown therein y' 1 is the same as the equipment shown and described in connection -With Fig. 1, eXcept that in Fig. 2 the duplex arrangement of the telegraph circuit is on the basis of the |w'ell known bridge plan.' For convenience, the same reference characters, as employed in Fig. 1, have been used in so :Ear as they apply to designate like parts in this figure of the drawing. l

In the bridge duplex equipment resistance units 15 and 16 serve as arms intermediate which the neutral point `5 may be connected b y a conductor 6 to suitableA telegraphi'c transmitting apparatus (not shown). Ad-

justment'of the variable devices 1'1, 12 and 13 of the artificial line conductor 1G to establish this line in electrical balance with the main line conductor 1 results in a aero potential etfect at theterminals of the line relay 2 for outgoing telegraphic impulses transmitted over the conductor 6.- Incoming lmpulses from the line conductor 1 complete circuit through the windings of the line relay 2,

thence over the articial line 10 to earth.

Since the incoming impulses act accumulacontrol relays 25-35 provides-that ollowu ing initial operation of either relay it will become self-locked and thereby continue energized -irrespective of theoperating circuit first established through its associated ammeter needle. Such operation may be traced by assuming a meter deflection to include the needle 21 with its contact 23, whereby the current source 24 .will be established through the winding of relay 25 to earth. Operation of the relay 25 andthe closing of its contacts 26 establish the current source 45 over the switch contacts 40, 41 (now closed), through theq winding of the relay 25 to earth, and since the signal 27 is connected in parallel with the winding of the relay 25, this signal will accordingly be displayed until such time as the switch member 40 is 'moved to disconnect the relay 25. It .will be obvious that the locking circuit of the relay 2'5`may be extended to control in y the duplex system.

As indicated, quick operation and slow re` leasing of the relays 25, 35 and 44 may be desirable under usual service conditions to give an obvious advantage in connection with the operation of the signals 27, 37 and 47. The switch 40 is provided for cutting out` all signals if desired or when thrown to its contact 41 this switch substitutes the Current source 43 for the current source 44, which is routed through the-relay 45, thereby cutting out thesignal 47 only.

It may be pointed out that the present system 1s ofespecial value in connection with multiplex telegraph working wherein heavy trafic in'multiple channel operation,

'as quadruplex, octopl'ex, etc., would not ordinarily require to'be interrupted in case it may benecessary to readjust the artiicial Eine to overcomean unbalance of the duplex circuits. Such service advantages may readily obtain. thro i adjusting the contacts of? the ammeters to present a gap space with respect to maximum deection of the needle vat under the normal strength of telegraphic impulses during proper balance of the circuits, and at the same time providing that such gap space be .Within the margmsof current range through which actual mutilation lof the telegraphic signals Would'not take place. Under such adjustments it will v`be clear that the signal system would serve as an advance Warning to permit adjustments to be made in the Variable'circuits of' the artificial line in advance of an'unbalanced condition reaching'a point at which telegraphic signals Would'be mutilated or perhaps interrupted.

t .will be further understood that it Would` be possible to employ a differential current meter provided with contacts and connected at the apex or neutral point of a duplex circuit, or an ammeter 'with contacts may be .connected'in series With a polar relay across nating current ammeters may be substituted for the vdirect current ammeters shown, and that such ammeters may preferably be of the so-called dead beat type. Contacts suitably i lwith said line conductor, an artiicial line,.

' controlling the operation ofsaid signal oo n assenze arran ed to be controlled'by the needleof the ia ternating current ammeters would readily applyto the control of-signaling circuits, which may be substantially `fthe same as. those illustrated herein.

What is claimed is: l. ln atelegraph duplex equipment, a main line conductor, an ammeter included an ammeter included With-said artificial line, a line relay included with` said mam line and said artificial line, contacts controlled by said ammeters, relays controlled by said ammeter contacts, an'd signals under control of'said'relays; v. y

4lin aduplex telegraph system, amain line, an artificial line, a relay' includedwithsaid main line and said artificial line responsive to incoming signals, but unresponsive to outgoing impulses by Way of said main line, an ammeter in said main line and an vammeter in said artificial line responsive 4 to both incoming and outgoing" impulses by 1 Way of said main line signal control relays, ce; and contacts controlled by said am'meters foi' y n trol relays. v a i In witness whereof, I hereuntosnbscri'fe my name this 31st`day of July, A, D., .191475530 Josu Huma Bn-na, 

